In power semiconductor devices, for example IGFETs (insulated gate field effect transistors) a load current typically flows in a vertical direction between two load electrodes formed at opposing sides of a semiconductor die. In a blocking mode field plate structures extending from one side into the semiconductor die deplete a drift portion of the semiconductor die and facilitate higher dopant concentrations in the drift portion without adverse impact on the blocking capability. Shrinking the field plate structures to needle-shaped field plate structures increases an active transistor area and allows for increasing the total channel width by forming a gridlike gate structure between the field plate structures.
It is desirable to improve yield and reliability of semiconductor devices with needle-shaped field plate structures.